evans



Jan. 24. 1956 F- M. EVANS LIQUID FUEL PUMPS 2 Sheets-Sheet 1 Filed Jan.21, 1955 Ire/ u ezzfol Jan. 24, 1956 EVANS 2,731,917

LIQUID FUEL PUMPS Filed Jan. 21, 1953 2 Sheets-Sheet 2 United Statesmnto LIQUID FUEL PUMPS Fraser Mackie Evans, Acton, London, England,assignor to C. A. V. Limited, Acton, London, England Application January21, 1953, Serial No. 332,302 Claims priority, application Great BritainJanuary 25, 1952 4 Claims. (Cl. 103-41) This invention relates tovariable-delivery liquid fuel pumps for internal combustion engines, ofthe kind in which a reciprocatory plunger has mounted on it a slidablyadjustable sleeve for controlling a spill passage in the plunger.

According to the present invention there is provided in association withthe plunger, a spill chamber, a sleeve slidable on the plunger forcontrolling communication between the spill passage in the plunger andthe spill chamber, and a spring-loaded axially movable and rotatablecontrol member, axial movement of this member in response to thepressure of the liquid in the spill chamber serving to move the sleeverelatively to the plunger, and angular movement of the said member bymanuallyoperable means, serving to vary the elfective area of the outletfrom the spill chamber.

In the accompanying drawings:

Figure 1 is a sectional side elevation of a pump embodying theinvention, and Figure 2 is a cross section on the line 2.2, Figure 1.

Figure 3 is a perspective view of the control member, this being drawnto a larger scale than in Figure 1.

Figure 4 is a fragmentary sectional side elevation illustrating amodification of .the construction shown in Figure 1.

Referring to Figures 1-3, there is provided in the body a of the pump, aspill chamber b through which extends the pump plunger 0. On the part ofthe plunger in the spill chamber is slidably mounted a sleeve d adaptedto control the spill passage 2 in the plunger, movement of the sleeverelatively to the plunger serving to determine the instant in the wor'ng stroke of the plunger at which the working chamber 1 at one end ofthe plunger is put into communication with the spill chamber forlimiting the quantity of liquid fuel discharged to the engine. Ifdesired the sleeve may be provided with a valve g loaded by a spring h,through which liquid from the plunger bore e can pass to the spillchamber.

Liquid fuel is supplied to the working chamber 7 through ports icommunicating with an annular feed chamber j, the latter being suppliedby a feed pipe k. Discharge of the fuel to the engine is effectedthrough a valve in loaded by a spring n.

In one side of the sleeve d is formed a cylindrical hole the axis ofwhich is inclined to the axis of the plunger, and in this hole iscontained a spherically formed end part p of a slidable and rotatablecontrol member q which is loaded by a spring r, the axis of this memberbeing at right angles to the plunger c. The control member serves bothas a sleeve-actuator and as a throttle, its axial movement serving toslide the sleeve along the plunger, and its angular movement serving tovary the effective area of the outlet from the spill chamber.

The portion q of the control member remote from the sleeve d is ofcylindrical form and is accommodated in a cylindrical guide s in thebody part. One end of this portion of the control member is exposed tothe spill chamber,

so that the control member can be moved against the action of theassociated spring by the pressure of the liquid in the spill chamber foradvancing the instant of opening of the spill passage e, movement in theopposite direction being effected by the spring. In the guide s isformed a channel 2 which serves as the outlet of the spill chamber,

and in the adjacent part of the control member is formed a recess 11(Figures 2 and 3) such that by rotation of the control member theeffective area of the entrance to the channel 2. can be varied. Ifdesired one edge v of the said recess u may be shaped as, for example,shown in Figure 3, so that axial movement of the control member can alsoserve to vary the effective area of the entrance to the channel I.

The desired angular movement to the control member is effected by acoaxially arranged hollow and angularly movable cylindrical member w towhich the control member is connected by a pin x engaging a slot y inthe member w. The said member w (hereinafter referred to as theactuating member) is movable both axially and angularly, and iscontained in a housing 2 formed on or secured to the body a of the pump.At its outer end it is provided with a manually operable lever 3 whichis movable between appropriately arranged stops 4. The actuating membercontains the spring r of the control member, and is itself held inendwise contact with an adjustable stop 5 by a spring 6 arranged aroundthe actuating member, this stop serving to determine the normal maximumfuelsupply position of the control member. To enable a temporaryincrease of fuel supply to be obtained in excess of the normal maximumwhen starting the engine that actuating member is moved axially. Theeffect of this movement enables the spring r to move the control memberto the left of the position shown in Figure 1, and so cause an upwardmovement to be given to the sleeve d, thereby increasing the distance ofthe outlet end of the spill passage 2 from the valve g.

The plunger 0 of the pump is reciprocated in the usual manner by thealternate actions thereon of a rotary cam 7 and a spring 8. Forproviding the normal maximum supply of fuel, the sleeve d occupies theposition shown in Figure 1. Towards the end of the discharge stroke ofthe plunger, the outlet end of the spill passage e in the plunger,coincides with the position of the valve g in the sleeve d, and soallows the remainder of the fuel in the working chamber of the pump tobe discharged to the spill chamber b. The fuel accumulated in thischamber passes to a drain pipe 9 attached to the part 2 at a ratedetermined by the setting of the control member q. So long as the pumpis operating at a relatively moderate rate the pressure of the fuel inthe spill chamber has no effect on the control member. But when the rateof working of the pump exceeds a predetermined amount for a givensetting of the control member (which is manually variable by the lever3), the fuel pressure in the spill chamber rises sufliciently toovercome the action of the spring r, and the control member is moved tothe right by the fuel pressure in the spill chamber, thereby causing theend part p of the control member to impart a downward movement to thesleeve d. This results in the spillage from the working chamber to occurat an earlier instant during the discharge stroke of the plunger c andreduces by the desired amount the quantity of fuel discharged to theengine.

In Figure 4 there is illustrated a modification of the con structionshown in Figure 1, for enabling the extra fuel temporarily required whenstarting the engine, to be obtained automatically. In the right hand ofthe control member q is formed a transverse slot 10 across which extendsa pin 11. The pin is loaded by a light spring 12 carried by the controlmember, and the outer ends of the pin engage slots y in the actuatingmember w. Also the said ends are loaded by the spring 13. When the pumpis at rest the various parts occupy the relative positions shown inFigure 4, and this condition remains so long as the fuel pressure in thespill chamber is zero, or remains sufficiently low to have .no eifecton'the spring 12. In this condition the sleeve d occupies its uppermostposition, wherein it allows a temporary excess of fuel to be supplied tothe engine. But with increasing speed the pressure in the spill chamberovercomes the .action of the spring .12 and moves the controlmember-until the closed end of the slot 10 abuts against the pin 11, socausing the sleeve :1 to be moved to its normal maximum supply position.Thereafter the control member operates in the manner abovedescribed.

In the arrangement shown in Figure 4, the stop 5 shown in Figure l is:not used. Instead the outer end of the actuating member w has a.slida'ble connection with the lever 3, and the normal maximum supplyposition is determined by an vadjustable nut '14 mounted on the outerend of the said member and arranged to abut against the outer .faceofthelever under the action of the spring 6.

Whilst in the foregoing there is described an application of theinvention .to a pump in which the plunger operates only with areciprocatory motion, the invention is applicable in like manner to apump in which the plunger receives both a reciprocatory and a rotarymotion, the reciprocatory motion serving to-effect the required pumpingaction, and the rotary motion serving to connect a delivery passage inthe plunger with each in turn of a number of delivery passages in thepump body, the latter being connected to the dilferent cylinders of amulti-cylinder engine.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A liquid fuel pump of the kind specified, comprising in combination abody having therein a spill chamber provided with an outlet, areciprocatory plunger extending through said spill chamber and having aspill passage therein, a sleeve slidable on said plunger for controllingcommunication between said spill passage and chamber,

and a spring-loaded axially movable and rotatable control memberengaging said sleeve and cooperating with said outlet so that axialmovement of said control member serves to move said sleeve relatively tosaid plunger, and angular movement of said control member serves to varythe effective area of said outlet.

2. A liquid fuel pump according to claim 1, in which the axis of thecontrol member is at right angles to the axis of the plunger, and inwhich the sleeve is formed with an inclined hole, one end of saidcontrol member being situated in :said hole, and serving to co-operatetherewith for imparting axial movement to said sleeve in response toaxial movement of said control member.

3. A liquid fuel pump according to claim 1, and having in combinationwith the sleeve-actuating control member which is movable axially byfuel pressure in the spill chamber, a guide provided with thespill-chamber outlet, and a manually operable angularly and axiallymovable actuating member operatively connected to said control membersothat the latter is capable of a limited amount of axial movementrelatively to said actuating member.

4. A liquid fuel pump according to claim 1, having in combination withthe sleeve-actuating control member which is movable axially by fuelpressure in the spill chamber, a guide provided with the spill-chamberoutlet, and a manually operable angularly and axially movable actuatingmember having a spring-loaded connection with the control member so thatthe latter is capable of a limited amount of axial movement relativelyto said actuating member which serves also, through the medium of saidconnection, to determine normal and temporary maximum fuel supplypositions of the sleeve.

References Cited in the file of this patent UNITED STATES PATENTS966,046 Noonan Aug. 2, 1910 1,877,803 Brown et al Sept. 20, 19322,282,562 Cole May 12, 1942

